Room previews doesn't work on federated rooms

[celiacheff]

When adding a room as an Tchap user, I expect to see to see a preview of the room before joining. But this is not working when the room is on another instance through federation.
This is what we get:

According to @guillaumevillemont, this is related to this bug: element-hq/element-web#12500, and can be solved with this patch https://github.com/matrix-org/matrix-react-sdk/pull/4132/files#

This bug is already present in production.